title: Impaired inhibition of prepotent motor actions in patients with Tourette syndrome.
abstract: BACKGROUND
  Evidence that tic behaviour in individuals with Tourette syndrome reflects difficulties inhibiting prepotent motor actions is mixed. Response conflict tasks produce sensitive measures of response interference from prepotent motor impulses and the proficiency of inhibiting these impulses as an act of cognitive control. We tested the hypothesis that individuals with Tourette syndrome show a deficit in inhibiting prepotent motor actions.
  
  
  METHODS
  Healthy controls and older adolescents/adults with persistent Tourette syndrome without a history of obsessive-compulsive disorder or attention-deficit/hyperactivity disorder and presenting with stable mood functioning (i.e., no history of well-treated anxiety or depression) participated in this study. They performed a Simon task that induced conflict between prepotent actions and goal-directed actions. A novel theoretical framework distinguished group differences in acting impulsively (i.e., fast motor errors) from the proficiency of inhibiting interference by prepotent actions (i.e., slope of interference reduction).
  
  
  RESULTS
  We included 27 controls and 28 individuals with Tourette syndrome in our study. Both groups showed similar susceptibility to making fast, impulsive motor errors (Tourette syndrome 26% v. control 23%; p = 0.10). The slope (m) reduction of the interference effect was significantly less pronounced among participants with Tourette syndrome than controls (Tourette syndrome: m = -0.07 v. control: m = -0.23; p = 0.022), consistent with deficient inhibitory control over prepotent actions in Tourette syndrome.
  
  
  CONCLUSIONS
  This study does not address directly the role of psychiatric comorbidities and medication effects on inhibitory control over impulsive actions in individuals with Tourette syndrome.
  
  
  CONCLUSIONS
  The results offer empirical evidence for deficient inhibitory control over prepotent motor actions in individuals with persistent Tourette syndrome with minimal to absent psychiatric comorbidities. These findings also suggest that the frontal-basal ganglia circuits involved in suppressing unwanted motor actions may underlie deficient inhibitory control abilities in individuals with Tourette syndrome.
authors.affiliation: Department of Neurology, Vanderbilt University, Nashville, TN 37232, USA. scott.a.wylie@vanderbilt.edu
authors.forename: Scott A
authors.initials: SA
authors.lastname: Wylie
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Claassen
authors.forename: Kristen E
authors.initials: KE
authors.lastname: Kanoff
authors.forename: K Richard
authors.initials: KR
authors.lastname: Ridderinkhof
authors.forename: Wery P M
authors.initials: WP
authors.lastname: van den Wildenberg
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance; D011930:Reaction Time; D005879:Tourette Syndrome / Q000523:psychology*